Initial support for FreeBSD platform:
- changes for the FreeBSD porto to be buildable from the master

NOTE: This patch will make the FreeBSD port buildable, but it will still
lack some features required for the port to be successfully runable.

Change-Id: Ie4aee423aa8656ee3b55f0ff89fbd92ed6c6c120
Authors: Grzegorz Bernacki, Michał Dubiel, Dominik Ermel